The accuracy of 4 different oximeters for continuous monitoring of mixed venous oxygen saturation during abdominal aortic surgery

: Several systems for mixed-venous oximetry are now available. There are one three-wave-length system (Abbott) and three two-wave-length systems with (Spectramed) and without automatic correction for hemoglobin or hematocrit (Edwards). The purpose of this prospective randomized study was to compare the different systems and to examine the accuracy of continuous mixed-venous oximetry during abdominal aortic surgery. Eighty patients had a radial artery cannula and one of the following fiberoptic pulmonary artery catheters inserted before induction of anesthesia: Swan-Ganz oximetry TD catheter (Edwards), Swan-Ganz flow-directed oximetry thermodilution paceport catheter (Baxter, Edwards Division), SpectraCath STP (Spectramed), and Opticath (Abbott). Mixed-venous O2 saturation was monitored by oximetry computers: SAT-1 (Edwards), SAT-2 (Baxter, Edwards Division), Hemopro2 (Spectramed), and Oximetrix 3 (Abbott). As a method of reference, mixed-venous blood samples were drawn and immediately analyzed by an OSM3-Hemoximeter. Data sets were obtained at eight predetermined times. Hemoglobin was kept constant at +/- 1 g.dl-1. Continuous oximetry in comparison to in-vitro measurements yielded a correlation coefficient of r = 0.873 (P less than 0.0001) and a value of bias and precision (b +/- p) of -0.9 +/- 2.6% for the SAT-1, r = 0.815 (P less than or equal to 0.0001) and b +/- p = -2.2 +/- 2.5% for the SAT-2, r = 0.901 (P less than or equal to 0.0001) and b +/- p = 0.35 +/- 2.5% for the Hemopro2, and r = 0.920 (P less than or equal to 0.0001) and b +/- p = 0.1 +/- 1.8% for the Oximetrix 3, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)